An automated analyzer is used in tests in various fields, such as in immunological tests, biochemical tests, and blood transfusion tests; performs analytical processing on multiple samples at the same time; and analyzes multiple components quickly with high precision.
Hitherto, an automated analyzer has included a nozzle cleaning mechanism for cleaning a probe in order to prevent a carry-over that influences analysis results from occurring when a liquid, such as a sample liquid or a reagent liquid, that has been dispensed first is carried over to a liquid that is subsequently dispensed while the liquid that has been dispensed first remains adhered to the probe. Such a nozzle cleaning mechanism is formed so as to supply a cleaning liquid to the probe. In a nozzle-cleaning method using the nozzle cleaning mechanism, after sucking and discharging the liquid and completing the dispensing, the probe is moved to the position of the nozzle cleaning mechanism, and the cleaning liquid is supplied to the probe to clean the probe.
For example, PTL 1 describes a nozzle cleaning technology in which a nozzle including a discharge nozzle and a suction nozzle is used to perform a cleaning operation including discharge and suction of a cleaning liquid at least two times. This nozzle is formed such that a lower end of the discharge nozzle is disposed above a lower end of the suction nozzle by a prescribed length.
In the technology described in PTL 1, when cleaning the nozzle, first, the nozzle is inserted into a cleaning tank such that a front end of the suction nozzle is positioned near a bottom portion of the cleaning tank. Next, a first liquid amount of cleaning liquid (first cleaning liquid) is injected into the cleaning tank by the discharge nozzle, and the first cleaning liquid is sucked by the suction nozzle. Then, a second liquid amount of cleaning liquid (second cleaning liquid) that exceeds the first liquid amount is injected into the cleaning tank by the discharge nozzle and the second cleaning liquid is sucked by the suction nozzle.
In this way, in the technology described in PTL 1, the cleaning liquid amount that is discharged during the cleaning is divided in at least two amounts, that is, the first cleaning liquid amount and the second cleaning liquid amount; and is discharged. The first cleaning liquid amount is an amount that allows the nozzle to be immersed up to a height at which a front end portion of the suction nozzle is immersed in a liquid, such as a reagent liquid or a sample liquid, when the nozzle is immersed in the liquid; and the second cleaning liquid amount is an amount at which the cleaning tank is approximately full. That is, in the technology described in PTL 1, a high-concentration contaminated region up to the aforementioned height from a lower end of the suction nozzle is cleaned by using the first cleaning liquid, and a low-concentration contaminated region up to a prescribed height from the lower end of the suction nozzle is cleaned by using the second cleaning liquid.